This invention relates in general to body and frame assemblies for vehicles. More specifically, this invention relates to an improved structure for a combined engine cradle and cross member structure for use with such a vehicular body and frame assembly.
Virtually all land vehicles in common use, such as automobiles, vans, and trucks, include a body and frame assembly which is supported upon a plurality of ground-engaging wheels by a resilient suspension system. The structures of known body and frame assemblies can be divided into two general categories, namely, separate and unitized. In a typical separate body and frame assembly, the structural components of the body portion and the frame portion are separate and independent from one another. When assembled, the frame portion of the assembly is resiliently supported upon the vehicle wheels by the suspension system and serves as a platform upon which the body portion of the assembly and other components of the vehicle can be mounted. Separate body and frame assemblies of this general type are found in most older vehicles, but remain in common use today for many relatively large or specialized use modem vehicles, such as large vans, sport utility vehicles, and trucks. In a typical unitized body and frame assembly, the structural components of the body portion and the frame portion are combined into an integral unit which is resiliently supported upon the vehicle wheels by the suspension system. Unitized body and frame assemblies of this general type are found in many relatively small modern vehicles, such as automobiles and minivans.
In both types of body and frame assemblies, it is known to provide a specialized structure for supporting the engine of the vehicle thereon. This engine support structure, which is commonly referred to as an engine cradle, is frequently embodied as a generally U-shaped member having a central portion and a pair of leg portions. Engine mount portions and body mount portions formed at various locations on the engine cradle. The engine mount portions are provided for facilitating the connection of the engine to the cradle, while the body mount portions are provided for facilitating the connection of the cradle to the body and frame assembly. Usually, bolts or similar fasteners are used to provide the various connections between the engine, the cradle, and the body and frame assembly. Thus, the engine cradle securely supports the engine on the body and frame assembly of the vehicle during use.
In the past, an engine cradle was usually formed by securing a number of individual components into a desired configuration. Typically, these individual components were metallic pieces which were stamped or otherwise shaped as desired, then welded together to form the final engine cradle. Engine cradles having this general structure have been found to be effective, but are relatively time consuming and expensive to manufacture because of the large number of individual components involved. More recently, engine cradles have been formed from a single tubular component using the process of expansion shaping, commonly referred to as hydroforming. Hydroforming is a well known process which uses pressurized fluid to deform a tubular member into a desired shape. To accomplish this, the tubular member is initially disposed between two die sections of a hydroforming apparatus which, when closed together, define a die cavity having a desired final shape. Thereafter, the tubular member is filled with a pressurized fluid, typically a relatively incompressible liquid such as water. The pressure of the fluid is increased to a magnitude where the tubular member is expanded outwardly into conformance with the die cavity. As a result, the tubular member is deformed into the desired final shape. Hydroforming is an advantageous process for forming engine cradles and other structures because it can quickly deform a single component into a desired shape.
Regardless of whether the engine cradle is formed from a number of individual welded components or from a single hydroformed component, it is often desirable to secure a cross member between the two leg portions of the engine cradle adjacent to the ends thereof. The cross member provides desirable lateral and torsional rigidity to the engine cradle as a whole. In the past, cross members for engine cradles have been formed from flat metallic members which have been stamped or otherwise shaped as desired. Although known cross members for engine cradles have been effective, it has been found that they must be formed from relatively heavy pieces of material in order to provide the desired lateral and torsional rigidity. As is well known, weight reduction is an important goal in the design of virtually all components contained in vehicles. Thus, it would be desirable to provide an improved structure for an engie cradle having a cross member secured thereto which is lighter in weight than known combined engine cradle and cross member structures, but which provides the necessary lateral and torsional rigidity thereto.